Traditionally, satellite communications have involved a fixed routing of uplink analog channels to downlink analog channels. The input and output multiplexers and up/down converters are prearranged to implement the frequency plan for uplink and downlink.
A full digital solution is more flexible, but can be far more costly. Moreover, a digital payload with phased array antennas (beam steerable) uses solid state power amplifiers that achieve lower power output density than the comparable analog technology.
Like reference numerals are used in the drawings to denote like elements and features.